1. Field of the Invention
The present invention relates to a multilayer printed wiring board and a method of manufacturing a multilayer printed wiring board.
2. Discussion of the Background
As to multilayer printed wiring boards, an idea for a multilayer printed wiring board wherein conductor circuits and interlaminar resin insulating layers are alternately laminated on a resin substrate referred to as a core has been brought up. Additionally, a connection between conductor circuits via an interlaminar resin insulating layer of a multilayer printed wiring board is accomplished with via conductors. Such a multilayer printed wiring board can be manufactured with a method described below, for example.
Namely, the multi-layer printed wiring board can be manufactured with a copper-clad laminate board wherein a copper foil is bonded on both faces of a resin substrate as a starting material, and lower-layer conductor circuits are first formed on the resin substrate. Next, an interlaminar resin insulating layer is formed on the resin substrate on which the lower layer conductor circuits have been formed. Further, opening portions are formed in the interlaminar resin insulating layer such that the lower layer conductor circuits on the resin substrate are exposed.
Subsequently, an electroless plating film is formed on the interlaminar resin insulating layer and the exposed faces in the opening portions, and after a plating resist has been formed on this electroless plating film, a thickness is added by electroplating such that upper layer conductor circuits are formed on the interlaminar resin insulating layer by etching after the plating resist has been stripped. The lower layer conductor circuits on the resin substrate and the upper layer conductor circuits on the interlaminar resin insulating layer are connected with via conductors.
Further, following the formation of the interlaminar resin insulating layer and the upper layer conductor circuits having been repeated, a solder resist layer is formed at the end in order to protect the conductor circuits such that a multilayer printed wiring board can be manufactured by solder bumps being formed for the connection of electronic components such as an IC chip, a mother board, etc. An example multilayer printed wiring board is described in JP 2005-347391, the contents of this publication being incorporated herein by reference in their entirety.